Question:
If vectors $\overrightarrow{\mathrm{a}}_{1}=\mathrm{x} \hat{\mathrm{i}}-\hat{\mathrm{j}}+\hat{\mathrm{k}}$ and $\overrightarrow{\mathrm{a}}_{2}=\hat{\mathrm{i}}+\mathrm{y} \hat{\mathrm{j}}+\mathrm{z} \hat{\mathrm{k}}$ are collinear, then a possible unit vector parallel to the vector $x \hat{i}+y \hat{j}+z \hat{k}$ is
Correct Option: , 4
Solution:
$\vec{a}_{1}$ and $\vec{a}_{2}$ are collinear
so $\frac{x}{1}=\frac{-1}{y}=\frac{1}{z}$
unit vector in direction of
$x \hat{i}+y \hat{j}+z \hat{k}=\pm \frac{1}{\sqrt{3}}(\hat{i}-\hat{j}+\hat{k})$